I have never ever had any problems with MIDI timing on a Roland XP or JV instrument period. Never EVER. No one else does either. I will explain what this is.
First off, I upgraded from the XP50 to the XP60. You'll appreciate the large graphic display. It displays more. You can see the shape of envelopes as you edit making things more intuitive. You can see more on the MICRO EDIT display. You can see the keyboard layout while doing RPS. The new display is very welcome.
You get four more controller sliders which can be assined as a mixer (for sequencing), fileter, resonance, attack and decay, or as anything else you want to assign them to.
Next, you get a click track output, four controler pedals as oppsed to two and two extra stero outputs as to assign different instruments to when mixing down.
Common used functions like SOLO, PORTAMENTO, OCTAVE, TRANSPOSE, etc. have individual keys so you don't have to access the edit menus to get these functions.
The Arpeggiators work just fine and are also a welcome feauture (I am trained and can played arpeggios so I don't use this feature much).
I think upgrading to the XP60 was a very good deal. Of course it is not necessary. The XP50 was a fine board. It's just easier to get around on this board.
The Infamous EPU.